here in MI.. many variations on the pasture grasses [i am not talking about foo foo fancy cultivars] ... turn purple in fall ... right before they turn brown.. and i mow then to the ground ... i would suggest that color alone is not definitive ....

i dont know how you could make an ID on your pic.. with no scale.. and no pic of a leaf ...

carol makes a stab in the dark.. and she is usually right.. but that doesnt look like a 1.5 to 3 foot tall hedge-like plant .... per the link ...